Changes:
- bpf_btf_get_next_id() API to iterate over system's BTF objects;
- libbpf_set_print() now returns previously set print callback;
- libbpf versioning, build, and packaging improvements;
- convenience helpers for working with BTF types;
- experimental BPF CO-RE relocation support;
- various AF_XDP fixes and enhancements;
- lots of bug fixes and small improvements all around the library from many contributors.
N.B. This is a first release of libbpf that uses symbol versioning. Please let us know if you encounter any issue because of that.